body, html {
  margin: 0;
  padding: 0;
  height: 100%;
  background: #f0f0f0;
  font-family: sans-serif;
}

.center {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  height: 100vh;
  text-align: center;
}

.btn {
  background: #007bff;
  color: white;
  padding: 15px 30px;
  margin-top: 20px;
  border: none;
  border-radius: 10px;
  text-decoration: none;
  font-size: 1.2rem;
  transition: 0.3s;
}

.btn:hover {
  background: #0056b3;
}

canvas {
  border: 2px solid #333;
  display: block;
  margin: 0 auto;
  touch-action: none;
}

.top-bar {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 10px;
  padding: 10px;
  background: #ffffff;
  box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}